Ginzuu Android 5.1.1 device is always losing exchange contacts in the third day. I have to delete and re-add the account.

[AC Question]

Ginzuu Android 5.1.1 device is always losing exchange contacts in the third day. I have to delete and re-add the account.

I have Ginzzu phone with Android 5.1.1. Sync account alwas going well without any problems. But in the third day all axcgange contacts desapear from the phone. I have to delet account and creat it again for three days. What can I do?